Main and auxiliary frequency conversion common direct current automatic switching speed regulation control system

Abstract

The invention relates to a main and auxiliary frequency conversion common direct current automatic switching speed regulation control system, and relates to the technical field of frequency converter pump interference electricity prevention, in particular to a main frequency converter connected with a first power supply, an auxiliary frequency converter connected with a second power supply, and the main frequency converter and the auxiliary frequency converter are connected with a motor; the auxiliary frequency converter is connected with a direct-current line of the main frequency converter; when the main frequency converter breaks down, the control unit controls the main frequency converter and the auxiliary frequency converter and controls the circuit between the main frequency converter and the motor to be disconnected and the circuit between the auxiliary frequency converter and the motor to be connected. When the motor breaks down, the control unit controls the circuit between the motor and the main frequency converter and the auxiliary frequency converter to be disconnected. The invention aims to solve the problems that the existing anti-interference electricity technology cannot realize 100% anti-interference electricity performance and has no frequency converter fault automatic switching capability, the investment is large, and the space of a substation device needs to be additionally occupied.

Description

Technical Field

[0001] The invention relates to the technical field of anti-electrical shaking of frequency converter pumps, and in particular to a main-auxiliary frequency conversion direct current automatic switching speed control system. Background Art

[0002] The power system is the source of power for refining and chemical enterprises. Excessive shaking can easily cause fluctuations in production equipment, and even fire and explosion accidents. Power-consuming enterprises have technical bottlenecks such as poor anti-swing capabilities of variable frequency speed regulating pumps and the inability to automatically switch to backup circuits without disturbance due to frequency conversion failures.

[0003] The furnace fans or important variable frequency pumps of the production equipment of the power-consuming enterprises generally adopt industrial variable frequency control. The normal operation variable frequency state realizes the automatic adjustment of the process and energy saving effect. The industrial frequency state is only used as a manual emergency standby operation mode when the frequency conversion fails. There are currently three common problems with this method: 1. The technical problem of the poor anti-power shaking ability of the furnace fan under the variable frequency operation state: when the external network shakes, the inverter itself has insufficient voltage crossing ability, causing the furnace fan to stop under the variable frequency operation state, causing the heating furnace process to fluctuate, and seriously causing the device to stop; 2. When the furnace fan inverter fails under the variable frequency operation state, it does not have the ability to automatically switch to the standby circuit; 3. The problem of unreliable control power supply, abnormal control function during power shaking, causing shutdown.

[0004] At present, there are five main technologies for frequency conversion pump anti-electrical shaking: 1. Permanent magnet speed regulation technology is used to solve the problem of anti-electrical shaking, but this technology cannot solve the problem of reducing pump load flow fluctuation during electric shaking, and is not suitable for low-flow interlocking pumps; 2. Dynamic voltage restorer technology is used to solve the problem of anti-electrical shaking. This technology is suitable for extremely important pumps with low-flow interlocking frequency conversion or non-frequency conversion. The investment cost is high and it takes up space on site; 3. The frequency converter's own voltage-crossing capability technology is used to solve the problem of anti-electrical shaking. The success rate of this technology is subject to the influence of many factors such as voltage fluctuation type, degree and load conditions, and it cannot guarantee that the pump will stop when the electric shaking occurs. It does not reduce the load and is not suitable for low-flow interlocking pumps. It needs to increase the delay when used for low-flow interlocking pumps. 4. The inverter DC bus support technology is used to solve the problem of anti-electrical shaking, but the investment in this technology is relatively large, and the additional investment is about 1,785 yuan / KW. The transformation needs to occupy a certain space in the substation; 5. The industrial frequency conversion automatic switching technology is used to solve the problem of anti-electrical shaking. This technology cannot guarantee that the pump will not reduce the load during electric shaking. It is not suitable for low-flow interlocking pumps. It needs to increase the delay when used for low-flow interlocking pumps. It is suitable for non-important inverter pumps with slow speed reduction to resist electric shaking. This technology is complex and requires the cooperation of automatic adjustment technology of the damper.

[0005] Comprehensive analysis of the above five inverter pump anti-electrical sway technologies shows that only the dynamic voltage restorer technology and the inverter DC bus support technology can achieve 100% anti-electrical sway performance, but they do not have the automatic switching function of inverter faults and require a large investment. Although the industrial inverter automatic switching technology has the automatic switching function, it does not have 100% anti-electrical sway performance, and the existing technologies do not meet the requirements. Summary of the invention

[0006] The present invention proposes a main-auxiliary variable frequency co-direct current automatic switching speed control system to solve the problems of existing anti-electrical shaking technology, which cannot achieve 100% anti-electrical shaking performance and does not have the ability to automatically switch when the frequency converter fails, and has large investment and requires additional space for substation equipment.

[0007] According to one aspect of the present invention, there is provided a main-auxiliary frequency conversion direct current automatic switching speed control system, comprising: a main frequency converter, an auxiliary frequency converter and a control unit; The input end of the main frequency converter is connected to a first power source, the input end of the auxiliary frequency converter is connected to a second power source, and the output ends of the main frequency converter and the auxiliary frequency converter are connected to a motor; The DC circuit of the auxiliary frequency converter is connected to the DC circuit of the main frequency converter; The control unit is connected to the main frequency converter and the auxiliary frequency converter respectively; In the initial state, the line between the auxiliary frequency converter and the motor is disconnected. When the main frequency converter fails, the control unit controls the main frequency converter and the auxiliary frequency converter, and controls the line between the main frequency converter and the motor to be disconnected, and controls the line between the auxiliary frequency converter and the motor to be connected; When the motor fails, the control unit controls the lines between the motor and the main inverter and the auxiliary inverter to be disconnected.

[0008] Preferably, the control unit comprises: a common control module, a main control module and an auxiliary control module; The main control module is respectively connected to the main frequency converter, the auxiliary control module, the common control module and the motor, the auxiliary control module is respectively connected to the auxiliary frequency converter and the motor, and the common control module is respectively connected to the main frequency converter, the auxiliary frequency converter, the main control module and the auxiliary control module; When an abnormality occurs in the main inverter, the main control module sends a parameter abnormality signal to the common control module and the auxiliary control module, and at the same time controls the line between the main inverter and the motor to be disconnected, the auxiliary control module controls the line between the auxiliary inverter and the motor to be connected, and the common control module controls the DC line between the main inverter and the auxiliary inverter to be disconnected; When an abnormality occurs in the motor, the main control module controls the line between the main inverter and the motor to be disconnected, and the auxiliary control module controls the line between the auxiliary inverter and the motor to be disconnected.

[0009] Preferably, the main control module comprises: a main frequency conversion contactor, a first intermediate relay and a third intermediate relay; The main frequency conversion contactor is provided on the connection line between the main frequency converter and the motor, and the main frequency conversion contactor is respectively connected to the first intermediate relay and the third intermediate relay; The main inverter is connected to the auxiliary control module and the common control module respectively through the third intermediate relay.

[0010] Preferably, the auxiliary control module comprises: an auxiliary frequency conversion contactor, a second intermediate relay, a fourth intermediate relay and an AC fast fuse; The auxiliary frequency conversion contactor is arranged on the connection line between the auxiliary frequency converter and the motor; The main control module is connected to the second intermediate relay, and the second intermediate relay is connected to the auxiliary frequency conversion contactor through the AC fast fuse; The input end of the motor is connected to the main frequency converter through the AC fast fuse; The fourth intermediate relay is respectively connected to the auxiliary frequency converter and the common control module.

[0011] Preferably, the auxiliary control module further comprises: a time delay relay; The time delay relay is connected to the second intermediate relay, and is used to delay the start of the second intermediate relay for a preset time after it is energized.

[0012] Preferably, the common control module comprises: a DC circuit breaker and a DC fast fuse; The DC fast fuse and the DC circuit breaker are arranged on the DC line connecting the main frequency converter and the auxiliary frequency converter; The DC circuit breaker is connected to the main control module.

[0013] Preferably, the main frequency converter and the auxiliary frequency converter are uncontrolled rectifier bridge type frequency converters.

[0014] Preferably, it also includes a remote control unit and a one-to-two signal isolator; The remote control unit is connected to the main frequency converter and the auxiliary frequency converter respectively through the one-to-two signal isolator; The remote control unit is connected to the main control module, the auxiliary control module and the common control module respectively.

[0015] Preferably, it further comprises: a fifth intermediate relay; The fifth intermediate relay input terminal is connected to the main frequency converter and the auxiliary frequency converter respectively; The output end of the fifth intermediate relay is connected to the remote control unit.

[0016] Preferably, it also includes: a static mutual cut-off switch; The input ends of the static mutual switching switch are respectively connected to the first power supply and the second power supply; The output end of the static mutual switching switch is connected to the control unit.

[0017] The present invention has at least the following beneficial effects: The present invention proposes a main-auxiliary variable frequency shared direct current automatic switching speed control system, which realizes 100% active anti-electrical shaking function by arranging two frequency converters respectively connected to two different bus sections to jointly drive a machine pump, and adopts the technology of mutual support of the two frequency converters sharing the direct current bus; by arranging a control unit to automatically identify and automatically switch to the auxiliary frequency converter when the main frequency converter fails, and automatically cut off the circuit between the main frequency converter and the auxiliary frequency converter, and automatically cut off the circuit between the main frequency converter and the auxiliary frequency converter and the motor when the motor fails, thereby preventing damage to the frequency converter and other components in the event of a failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings herein are incorporated into and constitute a part of the specification. These drawings illustrate embodiments consistent with the present invention and, together with the specification, are used to explain the technical solutions of the present invention.

[0019] Figure 1 A device connection block diagram of a main-auxiliary variable frequency direct current automatic switching speed regulation control system according to an embodiment of the present invention is shown; Figure 2 A circuit diagram of a main-auxiliary variable frequency direct current automatic switching speed control system according to an embodiment of the present invention is shown; Figure 3 A circuit diagram of a main control module according to an embodiment of the present invention is shown; Figure 4 A circuit diagram of an auxiliary control module according to an embodiment of the present invention is shown; Figure 5 A circuit diagram of a common control module according to an embodiment of the present invention is shown. Implementation

[0020] Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0021] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0022] The term "and / or" herein is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set consisting of A, B, and C.

[0023] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In some examples, methods, means, elements and modules well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0024] Figure 1 A device connection block diagram of a main-auxiliary variable frequency direct current automatic switching speed regulation control system according to an embodiment of the present invention is shown; Figure 2 A circuit diagram of a main-auxiliary variable frequency direct current automatic switching speed control system according to an embodiment of the present invention is shown; Figure 3 A circuit diagram of a main control module according to an embodiment of the present invention is shown; Figure 4 A circuit diagram of an auxiliary control module according to an embodiment of the present invention is shown; Figure 5 FIG. 2 shows a circuit diagram of a common control module according to an embodiment of the present invention. Figure 1-5 As shown, a main-auxiliary variable frequency co-direct current automatic switching speed control system comprises: a main inverter, an auxiliary inverter and a control unit; the input end of the main inverter is connected to a first power supply, the input end of the auxiliary inverter is connected to a second power supply, and the output ends of the main inverter and the auxiliary inverter are connected to a motor; the DC line of the auxiliary inverter is connected to the DC line of the main inverter; the control unit is respectively connected to the main inverter, the auxiliary inverter and the motor; in an initial state, the line between the auxiliary inverter and the motor is disconnected, and when the main inverter fails, the control unit controls the main inverter and the auxiliary inverter respectively, and controls the line between the main inverter and the motor to be disconnected, and controls the line between the auxiliary inverter and the motor to be connected; when the motor fails, the control unit controls the line between the motor and the main inverter and the auxiliary inverter to be disconnected.

[0025] In the embodiments of the present invention and Figure 1In the circuit, the first power supply is connected to the input terminal of the main inverter through the I-section bus and the main circuit breaker 1QF, and the second power supply is connected to the input terminal of the auxiliary inverter through the II-section bus and the auxiliary circuit breaker 2QF. When the motor needs to start normally, 1QF and 2QF are controlled to be closed, and the 380V three-phase AC power on the I-section bus and the II-section bus is supplied to the main inverter BP1 and the auxiliary inverter BP2 through the line. The main inverter starts according to the preset acceleration curve and controls the motor to run at a predetermined speed.

[0026] During normal operation, the line between the output end of the main inverter and the motor is connected, the line between the output end of the auxiliary inverter and the motor is disconnected, and the DC line between the main inverter and the auxiliary inverter is connected. After the AC current enters the main inverter and the auxiliary inverter, the main inverter and the auxiliary inverter first convert the AC power into DC power; at this time, because the line between the output end of the auxiliary inverter and the motor is disconnected, and the DC line of the auxiliary inverter is connected to the main inverter and the DC line to form a common DC line, the auxiliary inverter converts the AC power of the power supply into DC power, and then transmits it to the main inverter through the common DC line; the main inverter then converts the DC power converted by itself and the DC power transmitted by the auxiliary inverter into adjustable frequency AC power and transmits it to the motor for power supply.

[0027] When the first power supply is shaken or lost, the I-section busbar is powered off and the main inverter has no AC input. At this time, the II-section busbar and the auxiliary inverter continue to output DC power and transmit it to the main inverter through the common DC line, and then the main inverter converts it into AC power to power the motor, so that the main inverter can achieve uninterrupted full-load operation and eliminate any fluctuations in process parameters caused by shaking. When the second power supply is shaken or lost, the II-section busbar is powered off and the auxiliary inverter has no AC input, and the main inverter continues to power the motor.

[0028] If the main inverter fails during operation and the control unit receives an abnormal parameter signal from the main inverter, it controls the common DC line between the main inverter and the auxiliary inverter to be disconnected, and at the same time controls the main inverter and the motor line to be disconnected, and controls the line between the auxiliary inverter and the motor to be connected, so that the auxiliary inverter supplies power to the motor.

[0029] If the motor fails during operation and the control unit receives a motor fault signal, it controls the main inverter and auxiliary inverter to disconnect the lines between the motor to ensure the safety of the system power supply equipment.

[0030] In the present invention, the control unit includes: a common control module, a main control module and an auxiliary control module; the main control module is respectively connected to the main inverter, the auxiliary control module, the common control module and the motor, the auxiliary control module is respectively connected to the auxiliary inverter and the motor, and the common control module is respectively connected to the main inverter, the auxiliary inverter, the main control module and the auxiliary control module; when an abnormality occurs in the main inverter, the main control module sends a parameter abnormality signal to the common control module and the auxiliary control module, and at the same time controls the line between the main inverter and the motor to be disconnected, the auxiliary control module controls the line between the auxiliary inverter and the motor to be connected, and the common control module controls the DC line between the main inverter and the auxiliary inverter to be disconnected; when an abnormality occurs in the motor, the main control module controls the line between the main inverter and the motor to be disconnected, and the auxiliary control module controls the line between the auxiliary inverter and the motor to be disconnected.

[0031] In the embodiments of the present invention and Figure 2 In the process, at startup, the main control module controls the connection between the main inverter and the motor. In the initial state, the DC circuit between the main inverter and the auxiliary inverter is connected, and the line between the auxiliary inverter and the motor is disconnected. The motor is powered by the main and auxiliary DC inverters.

[0032] If the main inverter fails during operation and the main inverter parameters become abnormal, the main control module connected to it will receive the main inverter parameter abnormality signal and send it to the common control module and the auxiliary control module, and at the same time control the line between the main inverter and the motor to be disconnected; after the auxiliary control module receives the main inverter parameter abnormality signal, it controls the line between the auxiliary inverter and the motor to be connected; after the common control module receives the main inverter parameter abnormality signal, it controls the DC line between the main inverter and the auxiliary inverter to be disconnected.

[0033] If the motor fails during operation, the parameters of the main inverter will also become abnormal. At this time, the main control module will send the received main inverter parameter abnormal signal to the auxiliary control module, and at the same time control the line between the main inverter and the motor to be disconnected. The auxiliary control module will also receive the abnormal signal of the motor connected to it, and the auxiliary control module will control the line between the auxiliary inverter and the motor to be disconnected.

[0034] In the present invention, the main control module includes: a main frequency conversion contactor, a first intermediate relay and a third intermediate relay; the main frequency conversion contactor is arranged on the connection line between the main frequency converter and the motor, and the main frequency conversion contactor is respectively connected to the first intermediate relay and the third intermediate relay; the main frequency converter is respectively connected to the auxiliary control module and the common control module through the third intermediate relay.

[0035] In the embodiment 3 of the present invention, the first intermediate relay is connected to the power supply through the external start control switch. When starting, the external start control switch SB2 is closed, so that the normally open contact of the first intermediate relay 1KA1 is energized and closed, and the coil of the main inverter KM1 connected thereto is energized, and the contact of KM1 is closed, so that the line between the main inverter and the motor is connected.

[0036] When the main inverter BP1 is abnormal, its contacts R02A and R02C are energized and closed, so that the normally open contacts of the third intermediate relay 1KA3 connected to R02A and R02C are energized and closed; the current signal (main inverter parameter abnormality signal) is transmitted to the auxiliary control module and the common control module connected to it after passing through 1KA3. After receiving the electrical signal transmitted by 1KA3, the common control module controls the line between the main inverter and the auxiliary inverter to be disconnected; after receiving the electrical signal transmitted by 1KA3, the auxiliary control module controls the line between the auxiliary inverter and the motor to be connected. In this way, the line between the main inverter and the motor is quickly disconnected, and the auxiliary inverter is used to replace the main inverter to run continuously and uninterruptedly.

[0037] At the same time, when the normally open contact of 1KA3 is closed, its normally closed contact is disconnected, which will cause KM1 connected to the normally closed contact of 1KA3 to lose power and disconnect, thereby disconnecting the line between the main inverter BP1 and the motor.

[0038] A first external stop control switch SB1 is installed between the external start control switch SB2 and the power supply. When the equipment needs to be stopped urgently on site, SB1 can be manually controlled to disconnect and shut down.

[0039] In the present invention, the auxiliary control module includes: an auxiliary frequency conversion contactor, a second intermediate relay, a fourth intermediate relay and an AC fast fuse; the auxiliary frequency conversion contactor is arranged on the connection line between the auxiliary frequency converter and the motor; the main control module is connected to the second intermediate relay, and the second intermediate relay is connected to the auxiliary frequency conversion contactor through the AC fast fuse; the input end of the motor is connected to the main frequency converter through the AC fast fuse; the fourth intermediate relay is respectively connected to the auxiliary frequency converter and the common control module.

[0040] In the embodiments of the present invention and Figure 4 In the embodiment, the third intermediate relay 1KA3 is connected to the second intermediate relay 2KA1; the second intermediate relay 2KA1 is connected to the auxiliary frequency conversion contactor KM2 through the AC fast fuse 3FU1. In the initial state, the auxiliary frequency conversion contactor KM2 is in the open state, and the AC fast fuse 3FU1 is in the closed state.

[0041] When the main inverter BP1 is abnormal, the normally open contact of the third intermediate relay 1KA3 is closed, and the current signal is transmitted to the second intermediate relay 2KA1 connected to it through 1KA3, so that the contact of 2KA1 is closed, thereby closing the contact of the auxiliary frequency conversion contactor KM2 connected to it; after KM2 is closed, the line between the auxiliary inverter BP2 and the motor is connected, and the motor is stably powered through the auxiliary inverter BP2 and the second power supply.

[0042] When the motor is abnormal, the parameters of the main inverter will also be abnormal. At this time, if the power supply is switched to the auxiliary inverter through the main control module, the control circuit components may be damaged. When the motor is abnormal, it is necessary to cut off the lines between the main inverter and the auxiliary inverter and the motor at the same time to ensure the safety of the equipment. When the motor abnormality causes the main inverter parameters to be abnormal, the normally closed contact of the third intermediate relay 1KA3 of the main control module will be disconnected to control the disconnection of KM1 connected to it, and the line between the main inverter and the motor will be cut off; at this time, because the AC fast fuse 3FU1 is connected to the motor power supply line, when the motor is abnormal, the 3FU1 will quickly blow, thereby disconnecting the line between the second intermediate relay 2KA1 and KM2, so that KM2 cannot be closed through 1KA3, and the auxiliary inverter BP2 cannot start the circuit for power supply, ensuring the safety of the equipment.

[0043] When an abnormality occurs in the auxiliary frequency converter BP2, its contacts R02A and R02C are energized and closed, so that the contacts of the fourth intermediate relay 2KA3 connected to R02A and R02C are energized and closed, and the electrical signal (auxiliary frequency converter parameter abnormality signal) is transmitted to the common control module through 2KA3. The common control module controls the line between the main frequency converter BP1 and the auxiliary frequency converter BP2 to be disconnected.

[0044] The second intermediate relay 2KA1 is connected to the power supply through the second external stop control switch SB3. When the equipment needs to be stopped on site, SB3 can be manually controlled to disconnect and stop. SB3 and SB1 are linkage switches. When one of them is disconnected, the other is disconnected at the same time to cut off the circuit.

[0045] In the present invention, the common control module includes: a DC circuit breaker and a DC fast fuse; The DC fast fuse and the DC circuit breaker are arranged on the DC line connecting the main inverter and the auxiliary inverter; the DC circuit breaker is connected to the main control module.

[0046] In the embodiments of the present invention and Figure 5 In the embodiment, the DC circuit breaker 3QF1 is connected to the third intermediate relay 1KA3 and the fourth intermediate relay 2KA3 which are connected in parallel.

[0047] When operating normally, the DC circuit breaker 3QF1 is in a closed state. The DC current of the auxiliary inverter BP2 is transmitted to the main inverter BP1 through the DC circuit breaker 3QF1. When an abnormality occurs in the main inverter BP1 or the auxiliary inverter BP2, the normally open contact of the third intermediate relay 1KA3 of the main control module or the fourth intermediate relay 2KA3 of the auxiliary control module is closed, thereby transmitting the current to the DC circuit breaker 3QF. After the DC circuit breaker 3QF is energized, the normally closed contact jumps open, thereby cutting off the DC line between the main inverter and the auxiliary inverter.

[0048] The DC fast fuse 3FU2 is used. When a serious short circuit occurs in the main inverter BP1 or the auxiliary inverter BP2, the DC fast fuse 3FU2 on the common DC line will first blow to disconnect the DC line. Then the normally open contacts 1KA3 of the main control module or 2KA3 of the auxiliary control module will close and send out an abnormal parameter signal, causing the DC circuit breaker 3QF1 of the common control module to trip and further disconnect the DC line. At the same time, the main inverter contactor KM1 or the auxiliary inverter contactor KM2 will lose power and disconnect, and the main inverter or auxiliary inverter will complete the startup operation in the preset speed tracking startup mode.

[0049] The common control module also includes: a temperature sensor for detecting the real-time temperature in the control cabinet. When the real-time temperature in the control cabinet exceeds a preset temperature, an indicator light on the control cabinet lights up to give an alarm.

[0050] In the present invention, the main inverter and the auxiliary inverter are uncontrolled rectifier bridge type inverters.

[0051] In the embodiment of the present invention, the main and auxiliary frequency converters are selected to be uncontrolled rectifier bridge frequency converters capable of parallel connection of DC buses.

[0052] During normal operation, both inverters are powered, and the inverter rectifies the AC power input into DC power through an uncontrolled rectifier bridge. The two inverters share a DC bus through a DC fast fuse 3FU2 and a DC circuit breaker 3QF. Since the inverter is an uncontrolled rectifier bridge, there will be no problem of power feedback to the AC power supply side.

[0053] The present invention also includes a remote control unit and a one-to-two signal isolator; the remote control unit is connected to the main inverter and the auxiliary inverter respectively through the one-to-two signal isolator; the remote control unit is connected to the main control module, the auxiliary control module and the common control module respectively.

[0054] In the embodiments of the present invention and Figure 2In the process, the remote control unit DCS is connected to the main inverter and the auxiliary inverter through the wireless transmission module and the one-to-two signal isolator. When the main inverter and the auxiliary inverter start running, the remote control unit sends a 4-20mA speed control signal to the main inverter and the auxiliary inverter through the wireless transmission module and the one-to-two signal isolator, so that the main inverter and the auxiliary inverter synchronously receive the speed control signal; when the main inverter operates normally, the main inverter controls the motor to run at a predetermined speed and frequency according to the speed control signal. When the main inverter fails, KM1 disconnects and cuts off the line between the main inverter and the motor, and KM2 closes to connect the auxiliary inverter to the motor line. At this time, the auxiliary inverter can directly control the motor to run at a predetermined speed and frequency according to the continuously received speed control signal synchronized with the main inverter, achieving perfect docking without changing the external control.

[0055] The remote control unit DCS is connected to the remote control switch through the wireless transmission module, and the remote control switch is connected to the first intermediate relay and the power supply respectively. If the external start control switch SB2 is not used for starting, the remote control unit can send a start signal to the remote control switch to control the remote control switch to close, so that the line between the first intermediate relay and the power supply is connected, thereby closing KM1 and connecting the circuit between the main inverter and the motor, so as to realize the remote control start or shutdown of the main inverter.

[0056] The remote control unit DCS is connected to the sixth intermediate relay 3KA1 through the wireless transmission module; the external start control switch SB2 of the main control module and the remote control switch are connected to the first intermediate relay 1KA1 through the sixth intermediate relay 3KA1; the second intermediate relay 2KA1 of the auxiliary control module is connected to the third intermediate relay 1KA3 through the sixth intermediate relay 3KA1; in the initial state, the 3KA1 contact is in a closed state. When an emergency stop is required, the remote control unit DCS sends a stop signal to the sixth intermediate relay 3KA1 through the wireless transmission module, controls the contacts of the sixth intermediate relay 3KA1 to disconnect, thereby disconnecting the line between the first intermediate relay 1KA1 and the power supply, and disconnecting the line between the third intermediate relay 1KA3 and the second intermediate relay 2KA1, causing KM1 or KM2 to lose power and disconnect, cutting off the line between the main inverter or auxiliary inverter and the motor, and realizing remote control of the motor emergency stop.

[0057] The present invention further includes: a fifth intermediate relay; the input end of the fifth intermediate relay is respectively connected to the main frequency converter and the auxiliary frequency converter; the output end of the fifth intermediate relay is connected to the remote control unit.

[0058] In an embodiment of the present invention, the normally closed contact of the fifth intermediate relay 1KA4 is connected to the first intermediate relay 1KA1, and the normally open contact is connected to the auxiliary frequency converter. When the main frequency converter operates normally, its operating parameter 4-20mA output analog signal is sent to the remote control unit through the fifth intermediate relay and the wireless transmission module. When the main frequency converter fails, the contact of the first intermediate relay 1KA1 is disconnected, so that the normally closed contact of the fifth intermediate relay 1KA4 is disconnected, and the normally open contact is closed at the same time, and the line between the fifth intermediate relay 1KA4 and the auxiliary frequency converter is connected, and the 4-20mA operating parameter output analog signal of the auxiliary frequency converter is sent to the remote control unit through the fifth intermediate relay and the wireless transmission module. Through the fifth intermediate relay, the switching of the output operating parameter signals of the main frequency converter and the auxiliary frequency converter is realized, ensuring that the remote control unit can continuously receive and monitor the operation of the motor and the frequency converter when the frequency converter is switched.

[0059] In the present invention, the auxiliary control module further comprises: a time delay relay; the time delay relay is connected to the second intermediate relay, and is used to delay the start of the second intermediate relay for a predetermined time after the second intermediate relay is energized.

[0060] In the embodiments of the present invention and Figure 4 In the circuit, a time delay relay 2KT1 is provided between the second intermediate relay 2KA1 and the auxiliary frequency converter contactor KM2. When the contact of 2KA1 is closed, the time delay relay 2KA1 will be used to delay the closing of KM2, and the delay time is 0.5~1.5s. The delayed closing of KM2 is used to prevent the current from impacting the auxiliary frequency converter BP2. After the closing of other nodes during the delay process and the current is stable, the auxiliary frequency converter BP2 is started and powered by KM2. At the same time, during the delay process, the auxiliary frequency converter will track the real-time running frequency and speed of the motor. After starting, it can output voltage according to the current motor running frequency, and then control the motor to gradually run at the predetermined frequency to prevent the load flow from changing when the main and auxiliary frequency converters are switched; at the same time, when the main and auxiliary frequency converters are switched, the analog signal of the operating parameters output to the remote control unit will be interrupted for a short time. After the delay is performed by the time delay relay, it can ensure that the status signal of the remote control unit does not change, and prevent the temporary disappearance of the operating signal from causing a chain shutdown.

[0061] The present invention further includes: a static mutual switching switch; the input end of the static mutual switching switch is respectively connected to the first power supply and the second power supply; the output end of the static mutual switching switch is connected to the control unit.

[0062] In an embodiment of the present invention, the output ends of the static mutual switching switch are respectively connected to the main control module, the auxiliary control module and the common control module. In the initial state, the current of the first power supply is transmitted to the main control module, the auxiliary control module and the common control module through the static mutual switching switch for power supply. When the first power bus is shaken or loses power, the static mutual switching switch will automatically switch to the second power supply, and the second power supply will fully bear all loads to ensure the stability of the power supply of the control module, avoid shutdown of the secondary control module due to abnormal function caused by power shaking, and achieve 100% anti-power shaking performance. When the power supply of the first power supply is restored, the static mutual switching switch automatically switches to the first power supply for power supply.

[0063] When the present invention is implemented in a transformation, it is only necessary to remove the original frequency conversion cabinet main power supply, motor main cable, original on-site start-stop control cable, main control room DCS 4-20mA speed regulation signal, frequency converter output 4-20mA analog signal and other peripheral connection cables, remove the original frequency conversion cabinet, install the control cabinet of the present invention (including the main frequency converter and auxiliary frequency converter inside), connect two power cables, motor load cables, control cables, main control room DCS 4-20mA speed regulation signal and frequency converter output 4-20mA analog signal and other cables, and then add an auxiliary frequency converter main power supply to another section of the distribution cabinet with the same capacity circuit. There is no need to add additional control switches or occupying equipment. The main frequency converter and auxiliary frequency converter parameters of the present invention simultaneously optimize the frequency converter or motor overload processing mode to alarm and continue to run, optimize the frequency converter itself voltage crossing function parameters and other related parameters, and improve the reliability of the frequency converter operation.

[0064] It can be understood that the above-mentioned various method embodiments mentioned in the present invention can be combined with each other to form a combined embodiment without violating the principle logic. Due to space limitations, the present invention will not go into details.

[0065] Those skilled in the art will appreciate that, in the above method of specific implementation, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of the steps should be determined by their functions and possible internal logic.

[0066] Electricity-consuming enterprises generally adopt a dual power supply system, and the probability of a power shaking accident in two power supplies at the same time is very low. The present invention realizes a 100% active anti-power shaking function by using two inverters respectively connected to two different bus sections to jointly drive a pump (motor), and adopts a technology of mutual support of two inverters using a common DC bus. The main control module, auxiliary control module and common control module are adopted to realize automatic switching to the auxiliary inverter when the main inverter fails, realizing a 0-second automatic switching function.

[0067] The present invention realizes accurate identification of inverter faults and motor faults, disconnects the auxiliary control module circuit of the auxiliary inverter by melting the auxiliary normally closed point through the AC fast fuse, and avoids the phenomenon of mistakenly switching to the auxiliary inverter caused by abnormal parameters of the main inverter when the motor fails. When the main inverter or the auxiliary inverter fails seriously, the DC fast fuse quickly melts and cuts off the connected DC bus, and the main inverter fault outlet (contact R02A) is actuated to trip the DC circuit breaker and completely de-list the common DC bus of the main and auxiliary inverters, thereby cutting off the connection between the main and auxiliary inverters to ensure that the continuous operation of the inverter that has not failed is not affected. When the auxiliary inverter is running, the speed tracking method is used to realize the startup of the inverter to ensure continuous operation of the load.

[0068] The main and auxiliary frequency conversion direct current automatic switching speed control cabinet of the present invention adopts a unique design method to realize all control requirements without changing the external control conditions, that is, without adding a new field control switch, the DCS card parts in the operation room and the system, and has strong applicability. The main control module, the auxiliary control module and the public control module are designed separately to avoid the control abnormality of other units caused by the failure of one unit to the greatest extent. At the same time, the present invention adds the remote start and stop control function of the operation room (remote control unit), which can realize remote control and has a high degree of automation.

[0069] Comparison of the economic efficiency of the present invention: Taking a 380V, 132KW machine pump as an example, to achieve 100% anti-electrical shaking performance, the most economical inverter DC support technology among the original inverter active anti-electrical shaking technologies requires 275,000 yuan, and this technology does not have the function of automatically switching to the backup circuit when the inverter fails. If the technical solution of the present invention is adopted, it only requires 140,000 yuan, and at the same time has the function of automatically switching to the auxiliary frequency conversion when the main inverter fails, and the investment cost is reduced by 50.9%. It has good economy, advanced control, complete functions, reliable technology, and the safety of production operation is improved to 100%, avoiding the shutdown of the machine pump due to electric shaking or failure of the main inverter during operation, causing fluctuations in production equipment, and avoiding production safety and environmental accidents caused by medium leakage, which has important safety and social benefits. The present invention is particularly suitable for key single important variable frequency machine pumps, and is suitable for wide promotion and application in important variable frequency machine pump sites of power-consuming enterprises.

[0070] The main and auxiliary frequency conversion co-direct automatic switching speed control system of the present invention has been applied to three important furnace fans in three sets of equipment, and the operation effect is good. It can realize automatic adjustment control and energy saving effect, with a high level of automation; it ensures that the pump does not reduce the load and has no impact when the power is shaken; it can automatically switch to the auxiliary frequency converter when the main frequency converter fails, and the reliability of continuous operation is high; with the minimum investment, it is the best solution to meet the two functions of 100% frequency conversion anti-power shaking performance and automatic switching of auxiliary frequency conversion when the frequency conversion fails; the overall distribution cabinet is integrated, and the transformation process is simple and easy to operate.

[0071] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A main and auxiliary frequency conversion direct current automatic switching speed control system, characterized in that: include: Main inverter, auxiliary inverter and control unit; The input end of the main frequency converter is connected to a first power source, the input end of the auxiliary frequency converter is connected to a second power source, and the output ends of the main frequency converter and the auxiliary frequency converter are connected to a motor; The DC circuit of the auxiliary frequency converter is connected to the DC circuit of the main frequency converter; The control unit is connected to the main frequency converter and the auxiliary frequency converter respectively; In the initial state, the line between the auxiliary frequency converter and the motor is disconnected. When the main frequency converter fails, the control unit controls the main frequency converter and the auxiliary frequency converter, and controls the line between the main frequency converter and the motor to be disconnected, and controls the line between the auxiliary frequency converter and the motor to be connected; When the motor fails, the control unit controls the lines between the motor and the main inverter and the auxiliary inverter to be disconnected.

2. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 1 is characterized in that: The control unit includes: a common control module, a main control module and an auxiliary control module; The main control module is respectively connected to the main frequency converter, the auxiliary control module, the common control module and the motor, the auxiliary control module is respectively connected to the auxiliary frequency converter and the motor, and the common control module is respectively connected to the main frequency converter, the auxiliary frequency converter, the main control module and the auxiliary control module; When an abnormality occurs in the main inverter, the main control module sends a parameter abnormality signal to the common control module and the auxiliary control module, and at the same time controls the line between the main inverter and the motor to be disconnected, the auxiliary control module controls the line between the auxiliary inverter and the motor to be connected, and the common control module controls the DC line between the main inverter and the auxiliary inverter to be disconnected; When an abnormality occurs in the motor, the main control module controls the line between the main inverter and the motor to be disconnected, and the auxiliary control module controls the line between the auxiliary inverter and the motor to be disconnected.

3. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 2 is characterized in that: The main control module includes: a main frequency conversion contactor, a first intermediate relay and a third intermediate relay; The main frequency conversion contactor is provided on the connection line between the main frequency converter and the motor, and the main frequency conversion contactor is respectively connected to the first intermediate relay and the third intermediate relay; The main inverter is connected to the auxiliary control module and the common control module respectively through the third intermediate relay.

4. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 2 is characterized in that: The auxiliary control module includes: an auxiliary frequency conversion contactor, a second intermediate relay, a fourth intermediate relay and an AC fast fuse; The auxiliary frequency conversion contactor is arranged on the connection line between the auxiliary frequency converter and the motor; The main control module is connected to the second intermediate relay, and the second intermediate relay is connected to the auxiliary frequency conversion contactor through the AC fast fuse; The input end of the motor is connected to the main frequency converter through the AC fast fuse; The fourth intermediate relay is respectively connected to the auxiliary frequency converter and the common control module.

5. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 4 is characterized in that: The auxiliary control module also includes: a time delay relay; The time delay relay is connected to the second intermediate relay, and is used to delay the start of the second intermediate relay for a preset time after it is energized.

6. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 2 is characterized in that: The common control module includes: a DC circuit breaker and a DC fast fuse; The DC fast fuse and the DC circuit breaker are arranged on the DC line connecting the main frequency converter and the auxiliary frequency converter; The DC circuit breaker is connected to the main control module.

7. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 1 is characterized in that: The main frequency converter and the auxiliary frequency converter are uncontrolled rectifier bridge type frequency converters.

8. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 2 is characterized in that: Also included are a remote control unit and a one-to-two signal isolator; The remote control unit is connected to the main frequency converter and the auxiliary frequency converter respectively through the one-to-two signal isolator; The remote control unit is connected to the main control module, the auxiliary control module and the common control module respectively.

9. The main and auxiliary frequency conversion direct current automatic switching speed control system according to claim 8 is characterized in that: Also includes: a fifth intermediate relay; The fifth intermediate relay input terminal is connected to the main frequency converter and the auxiliary frequency converter respectively; The output end of the fifth intermediate relay is connected to the remote control unit.

10. The main and auxiliary frequency conversion direct current automatic switching speed control system according to any one of claims 1 to 9, characterized in that: Also includes: Static mutual cut-off switch; The input ends of the static mutual switching switch are respectively connected to the first power supply and the second power supply; The output end of the static mutual switching switch is connected to the control unit.

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